Projection display with a cube wire-grid polarizing beam splitter

Abstract

A display apparatus includes a cube wire-grid polarizing beam splitter with a plate wire-grid polarizer disposed between a pair of prisms secured together to form a cube. A reflective spatial light modulator produces an image bearing color light beam. The cube wire-grid polarizing beam splitter is disposable in the image bearing color light beam to separate the image information and to produce a polarized image bearing color light beam. A pair of continuous film layers is disposed between the plate wire-grid polarizer and a forward prism with a forward layer adjacent the forward prism having a refractive index greater than both i) a refractive index of a rear layer adjacent the plate wire grid polarizer, and ii) a refractive index of the forward prism. A layer of ribs is disposed between the wires and a rear prism, and the ribs being aligned with and supporting the wires.

1 . A display apparatus, comprising:
 a) a light source to produce a light beam;   b) at least one cube wire-grid polarizing beam splitter disposable in the light beam to transmit a polarized light beam, and including a plate wire-grid polarizer disposed between a pair of prisms secured together to form a cube;   c) at least one reflective spatial light modulator disposable in the polarized light beam to encode image information thereon to produce an image bearing light beam;   d) the cube wire-grid polarizing beam splitter being disposable in the image bearing light beam to separate the image information and to produce a polarized image bearing light beam;   e) projection optics disposable in the polarized image bearing light beam;   f) a pair of continuous film layers disposed between the plate wire-grid polarizer and a forward prism with a forward layer adjacent the forward prism having a refractive index greater than both i) a refractive index of a rear layer adjacent the plate wire grid polarizer, and ii) a refractive index of the forward prism; and   g) a layer of ribs disposed between the wires and a rear prism, and the ribs being aligned with and supporting the wires.   
     
     
         2 . An apparatus in accordance with  claim 1 , wherein the spatial light modulator is disposed immediately adjacent the cube wire-grid polarizing beam splitter. 
     
     
         3 . An apparatus in accordance with  claim 1 , further comprising a combining prism disposed between the cube wire-grid polarizing beam splitter and the projection optics. 
     
     
         4 . An apparatus in accordance with  claim 1 , wherein an optical distance between the spatial light modulator and the projection optics is less than approximately 3 inches. 
     
     
         5 . An apparatus in accordance with  claim 1 , wherein the cube wire-grid polarizing beam splitter is oriented to face the spatial light modulator. 
     
     
         6 . An apparatus in accordance with  claim 1 , wherein the cube wire-grid polarizing beam splitter and the spatial light modulator are oriented and configured to reflect the polarized image bearing color light beam from the beam splitter. 
     
     
         7 . An apparatus in accordance with  claim 1 , wherein the cube wire-grid polarizing beam splitter and the spatial light modulator are oriented and configured to transmit the polarized image bearing color light beam through the beam splitter. 
     
     
         8 . An apparatus in accordance with  claim 1 , wherein the light source includes an LED array. 
     
     
         9 . An apparatus in accordance with  claim 1 , further comprising:
 a) beam shaping optics disposable in the light beam;   b) at least one color separator disposable in the light beam to separate the light beam into color light beams;   c) the at least one cube wire-grid polarizing beam splitter being disposable in one of the color light beams to transmit a polarized color light beam;   d) the at least one reflective spatial light modulator being disposable in the polarized color light beam to encode image information thereon to produce an image bearing color light beam;   e) the cube wire-grid polarizing beam splitter being disposable in the image bearing color light beam to separate the image information and to produce a polarized image bearing color light beam;   f) the projection optics being disposable in the polarized image bearing color light beam; and   g) a combining prism disposed between the cube wire-grid polarizing beam splitter and the projection optics.   
     
     
         10 . A modulation optical system, comprising:
 a) a reflective spatial light modulator configured to selectively encode image information on a polarized incident light beam to encode image information on a reflected beam;   b) a cube wire-grid polarizing beam splitter disposed adjacent the reflective spatial light modulator to provide the polarized incident light beam to the reflective spatial light modulator, and to separate the image information from the reflected beam to produce a polarized image bearing light beam, and including a plate wire-grid polarizer disposed between a pair of prisms secured together to form a cube;   c) a pair of continuous film layers disposed between the plate wire-grid polarizer and a forward prism with a forward layer adjacent the forward prism having a refractive index greater than both i) a refractive index of a rear layer adjacent the wires, and ii) a refractive index of the forward prism; and   d) a layer of ribs disposed between the wires and a rear prism, the ribs being aligned with and supporting the wires.   
     
     
         11 . A system in accordance with  claim 10 , further comprising:
 a) a light source to produce a light beam;   b) beam shaping optics disposable in the light beam;   c) at least one color separator disposable in the light beam to separate the light beam into color light beams; and   d) projection optics disposable in the polarized image bearing light beam.   
     
     
         12 . A system in accordance with  claim 11 , further comprising a combining prism disposed between the cube wire-grid polarizing beam splitter and the projection optics. 
     
     
         13 . A system in accordance with  claim 11 , wherein an optical distance between the spatial light modulator and the projection optics is less than approximately 3 inches. 
     
     
         14 . A system in accordance with  claim 10 , wherein the cube wire-grid polarizing beam splitter is oriented to face the spatial light modulator. 
     
     
         15 . A system in accordance with  claim 10 , wherein the cube wire-grid polarizing beam splitter and the spatial light modulator are oriented and configured to reflect the polarized image bearing color light beam from the beam splitter. 
     
     
         16 . A system in accordance with  claim 10 , wherein the cube wire-grid polarizing beam splitter and the spatial light modulator are oriented and configured to transmit the polarized image bearing color light beam through the beam splitter. 
     
     
         17 . A method of shortening a back focal length of a rear-projection display apparatus, comprising:
 a) obtaining a cube wire-grid polarizer with a wire-grid polarizer disposed between two prisms, a pair of continuous thin films between the wire-grid polarizer and a forward prism, with a forward film adjacent the forward prism having a refractive index greater than a refractive index of a rear film adjacent the wire-grid polarizer;   b) disposing a reflective spatial light modulator adjacent the cube wire-grid polarizer, and orienting the cube wire-grid polarizer with the pair of continuous thin films between the reflective spatial light modulator and the wire-grid polarizer;   d) disposing a recombination prism adjacent the cube wire-grid polarizer;   e) disposing projection optics adjacent the recombination prism; and   f) spacing the reflective spatial light modulator, the cube wire-grid polarizer, the recombination prism, and the projection optics closer together than without the prisms.   
     
     
         18 . A method in accordance with  claim 17 , wherein a distance between the spatial light modulator and the projection optics is less than approximately 3 inches. 
     
     
         19 . A modulation optical system, comprising:
 a) a spatial light modulator configured to selectively encode image information on a polarized incident light beam to encode image information on a beam;   b) a cube wire-grid polarizing beam splitter disposed adjacent the reflective spatial light modulator to separate the image information from the beam, and including a plate wire-grid polarizer disposed between a pair of prisms secured together to form a cube;   c) a pair of continuous film layers disposed between the plate wire-grid polarizer and a forward prism with a forward layer adjacent the forward prism having a refractive index greater than both i) a refractive index of a rear layer adjacent the wires, and ii) a refractive index of the forward prism; and   d) a layer of ribs disposed between the wires and a rear prism, the ribs being aligned with and supporting the wires.